In exchanging an empty bobbin for a full bobbin on a yarn winding unit for winding a yarn reserve thereon, the practice is known of severing the yarn leading to the full bobbin, feeding the remaining end of the yarn to a yarn holding device, then after exchange of the full bobbin for an empty pirn to seize the yarn extending to the yarn holding device and draw it out as far as the empty pirn and pinch it between the end of the empty pirn and a part adjoining the latter, which revolves with the empty pirn, whereupon the yarn extending between the yarn holding device and the point of pinch is severed at a fixed distance from the empty pirn (West German OS No. 23 32 327). Since the yarn holding device, particularly with thicker yarns, cannot continue to draw off the yarn when drawn out to the pirn because of the sharp deflection of the yarn over the edge of the grabber, the yarn dams up in an uncontrolled way between the draw-off rolls and the grabber, which may lead to difficulties in winding, at least until the excess length of yarn is consumed. These disadvantages are to be eliminated in accordance with the present invention.
Accordingly, an important object of the present invention is to eliminate any yarn damming during a bobbin change between the draw-off rolls and the yarn grabber, and to insure that the yarn gets safely wound onto the new pirn at the start.
Another important object of the present invention is the provision of apparatus for use with yarn winding machinery to eleiminate any yarn damming during a bobbin change.